Abstract

We use scaled clay models to study the temporal evolution of fault populations in experiments of moderately oblique (α = 60°) and highly oblique (α = 30°) distributed extension, where α is the angle between the rift axis and the direction of displacement. Faults nucleate at random heterogeneities, enhancing nucleation of diffuse clusters of new faults. In the highly oblique model, clusters of displacement-normal faults form parallel arrays, leading to fault growth dominated by tip propagation and along-strike linkage until maximum length is achieved. Subsequent growth of rift-subparallel faults leads to a phase of growth characterized by linkage and formation of branching faults. In the moderately oblique model, clusters form in a stepping geometry, leading to growth dominated by linkage. Faults nucleate and grow more rapidly, and their growth is less restricted than in the highly oblique model. Our results have implications for the maximum size earthquake to be expected in an oblique rift setting.